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35 pages, 1745 KiB  
Article
Balanced Fertilization of Winter Wheat with Potassium and Magnesium—An Effective Way to Manage Fertilizer Nitrogen Sustainably
by Agnieszka Andrzejewska, Katarzyna Przygocka-Cyna and Witold Grzebisz
Sustainability 2025, 17(15), 6705; https://doi.org/10.3390/su17156705 - 23 Jul 2025
Viewed by 412
Abstract
In agricultural practice, in addition to determining the nitrogen (Nf) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such [...] Read more.
In agricultural practice, in addition to determining the nitrogen (Nf) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such as magnesium (Mg) and sulfur (S). This hypothesis was verified in a single-factor field experiment with winter wheat (WW) carried out in the 2015/2016, 2016/2017, and 2017/2018 growing seasons. The experiment consisted of seven variants: absolute control (AC), NP, NPK-MOP (K as Muriate of Potash), NPK-MOP+Ki (Kieserite), NPK-KK (K as Korn–Kali), NPK-KK+Ki, and NPK-KK+Ki+ES (Epsom Salt). The use of K as MOP increased grain yield (GY) by 6.3% compared to NP. In the NPK-KK variant, GY was 13% (+0.84 t ha−1) higher compared to NP. Moreover, GYs in this fertilization variant (FV) were stable over the years (coefficient of variation, CV = 9.4%). In NPK-KK+Ki+ES, the yield increase was the highest and mounted to 17.2% compared to NP, but the variability over the years was also the highest (CV ≈ 20%). The amount of N in grain N (GN) increased progressively from 4% for NPK-MOP to 15% for NPK-KK and 25% for NPK-KK+Ki+ES in comparison to NP. The nitrogen harvest index was highly stable, achieving 72.6 ± 3.1%. All analyzed NUE indices showed a significant response to FVs. The PFP-Nf (partial factor productivity of Nf) indices increased on NPK-MOP by 5.8%, NPK-KK by 12.9%, and NPK-KK+Ki+ES by 17.9% compared to NP. The corresponding Nf recovery of Nf in wheat grain was 47.2%, 55.9%, and 64.4%, but its total recovery by wheat (grain + straw) was 67%, 74.5%, and 87.2%, respectively. In terms of the theoretical and practical value of the tested indexes, two indices, namely, NUP (nitrogen unit productivity) and NUA (nitrogen unit accumulation), proved to be the most useful. From the farmer’s production strategy, FV with K applied in the form of Korn–Kali proved to be the most stable option due to high and stable yield, regardless of weather conditions. The increase in the number of nutritional factors optimizing the action of nitrogen in winter wheat caused the phenomenon known as the “scissors effect”. This phenomenon manifested itself in a progressive increase in nitrogen unit productivity (NUP) combined with a regressive trend in unit nitrogen accumulation (NUA) in the grain versus the balance of soil available Mg (Mgb). The studies clearly showed that obtaining grain that met the milling requirements was recorded only for NUA above 22 kg N t−1 grain. This was possible only with the most intensive Mg treatment (NPK-KK+Ki and NPK-KK+Ki+ES). The study clearly showed that three of the six FVs fully met the three basic conditions for sustainable crop production: (i) stabilization and even an increase in grain yield; (ii) a decrease in the mass of inorganic N in the soil at harvest, potentially susceptible to leaching; and (iii) stabilization of the soil fertility of P, K, and Mg. Full article
(This article belongs to the Special Issue Soil Fertility and Plant Nutrition for Sustainable Cropping Systems)
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19 pages, 3653 KiB  
Article
Impact of Phosphorus Fertilization on Leaching, Accumulation, and Microbial Cycling in New Apple Orchards
by Yuwen Shen, Haitao Lin, Rui Xue, Yanan Ma and Yan Song
Agronomy 2025, 15(4), 952; https://doi.org/10.3390/agronomy15040952 - 14 Apr 2025
Viewed by 592
Abstract
Field experiments spanning five years were conducted to convert barren mountainous land into apple orchards, testing five phosphorus (P) fertilization schemes: no inorganic P (NP0K), superphosphate (FP), water-soluble inorganic P (WSF), superphosphate with alkaline soil conditioner (SC), and superphosphate with grass interplanting (GC). [...] Read more.
Field experiments spanning five years were conducted to convert barren mountainous land into apple orchards, testing five phosphorus (P) fertilization schemes: no inorganic P (NP0K), superphosphate (FP), water-soluble inorganic P (WSF), superphosphate with alkaline soil conditioner (SC), and superphosphate with grass interplanting (GC). Fertilizer solubility and soil pH were found to significantly impact P leaching and accumulation. Among the schemes, WSF exhibited the highest P leaching loss (3.65–3.87%), while SC (2.17–2.79%) and GC (2.79–3.25%) minimized such losses. As soil pH declined over time, aluminum P (Al-P) replaced calcium P (Ca-P) as the dominant inorganic P fraction, while occluded P (O-P) increased, resulting in reduced P bioavailability. Soil organic carbon (SOC) and acid phosphatase activity positively influenced inorganic P fractions, whereas prolonged orchard establishment decreased fixed inorganic P content. Microbial P cycling genes were less abundant and showed negative correlations with soil nitrate-N, electrical conductivity, available P (Olsen P), and SOC. These findings highlight that grass interplanting with superphosphate (GC) is an optimal strategy to minimize phosphorus leaching, enhance soil phosphorus bioavailability, and reduce environmental risks, making it a sustainable approach for orchard management. Full article
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18 pages, 3576 KiB  
Article
Effects of Nitrogen Application Strategies on Yield, Nitrogen Uptake and Leaching in Spring Maize Fields in Northwest China
by Ying Wang, Jingjing He, Zongyuan Gao, Ruliang Liu, Yu Hong, Fang Wang, Xinping Mao, Tianxiang Xu, Lina Zhou and Jun Yi
Plants 2025, 14(7), 1067; https://doi.org/10.3390/plants14071067 - 31 Mar 2025
Viewed by 895
Abstract
Nitrogen (N) is an essential nutrient for crop growth, as N fertilizer application regulates crop nitrogen uptake, affecting leaf photosynthetic rates, crop growth, and yield formation. However, both N deficiency and excess can reduce corn yields. Hence, optimizing the N fertilizer application strategy [...] Read more.
Nitrogen (N) is an essential nutrient for crop growth, as N fertilizer application regulates crop nitrogen uptake, affecting leaf photosynthetic rates, crop growth, and yield formation. However, both N deficiency and excess can reduce corn yields. Hence, optimizing the N fertilizer application strategy is crucial for crop production. In this study, a field plot trial with five N fertilization application strategies was conducted in the maize field from 2021 to 2022 in the Ningxia Yellow Irrigation District, Northwest China. These strategies contain zero N application rates (CK, 0 kg ha−1), the farmer practical N fertilizer application strategy (FP, 420 kg ha−1), the optimized N fertilizer application strategy (OPT, 360 kg ha−1), organic fertilizer and chemical fertilizer combination application (ON, 300 kg ha−1), and controlled-release N fertilizer and 33 urea application (CN, 270 kg ha−1). The maize yield and N balance under each treatment were investigated to propose the optimized N application strategy. The results showed that the CN treatment’s grain yield (15,672 kg ha−1) was the highest in both years, which was 109.97% and 8.92% higher than the CK and FP treatments, respectively. The apparent utilization rate and partial productivity of N fertilizer decreased with the increase in the N application rate. Also, the apparent utilization rate of N fertilizer in CN was 23.02%, 19.41%, and 13.02% higher than the FP, OPT, and ON, respectively. Applying controlled-release urea and organic fertilizers improved the physical and chemical properties of the soil, increased the organic matter content and soil fertility, and ultimately increased the spring maize yield. Meanwhile, the TN, NO3-N, and NH4+-N concentrations in leaching water significantly correlated with the N application rate. With the extension of the maize growth period, the concentrations of TN, NO3-N, and NH4+-N in leaching water gradually decreased. The N leaching amount in FP was the highest, while the CN was the lowest. The NO3-N is the primary N leaching form, accounting for 46.78~54.68% of the TN leaching amount. Compared with the CN, the ON significantly increased the inorganic N content in the 0–40 cm soil layer, and it reduced the residual inorganic N content below 40 cm soil depths compared with FP and OPT treatments. Considering the relatively high spring maize yield and N utilization efficiency, as well as the relatively low N leaching amount and soil inorganic N residues, the ON and CN treatments with 270–300 kg ha−1 N application rate were the optimized N application strategies in the spring maize field in the study area. Full article
(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))
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20 pages, 4213 KiB  
Article
Preparation of Phosphogypsum–Bentonite-Based Slow-Release Potassium Magnesium Sulfate Fertilizer
by Zhizhi Zhang, Chunxiao Han, Changyuan Tao, Xing Fan and Renlong Liu
Agriculture 2025, 15(7), 692; https://doi.org/10.3390/agriculture15070692 - 25 Mar 2025
Cited by 2 | Viewed by 755
Abstract
The application of slow-release fertilizers is essential for improving fertilizer utilization efficiency and promoting sustainable agricultural development. Unlike traditional single organic polymer-coated or inorganic-coated fertilizers, this study utilized biodegradable modified polyvinyl alcohol (PVA) as a binder and cheap, readily available phosphogypsum–bentonite as an [...] Read more.
The application of slow-release fertilizers is essential for improving fertilizer utilization efficiency and promoting sustainable agricultural development. Unlike traditional single organic polymer-coated or inorganic-coated fertilizers, this study utilized biodegradable modified polyvinyl alcohol (PVA) as a binder and cheap, readily available phosphogypsum–bentonite as an inorganic coating material to develop a novel slow-release potassium magnesium sulfate fertilizer (SRPMSF). This study initially examined the influence of SA dosage on PVA properties. XRD, FTIR, TGA, and water resistance analyses revealed that sodium alginate exhibits good compatibility with polyvinyl alcohol, enhancing its heat and water resistance. Ultimately, PVA–SA-2 (1.2% sodium alginate) was chosen as the optimal binder for SRPMSF production. Furthermore, this study investigated the impact of bentonite on the physical and slow-release properties of the SRPMSF by varying the phosphogypsum-to-bentonite ratio. This experiment included five treatment methods: the treatments consist of SRPMSF-1 (0 g bentonite), SRPMSF-2 (phosphogypsum/bentonite ratio of 4:1), SRPMSF-3 (3:2), SRPMSF-4 (2:3), and SRPMSF-5 (1:4). A control group (PMSF) was also included. The results indicated that, as the bentonite content increased, both the particle size and compressive strength of the coated slow-release fertilizer increased, with the SRPMSF particle sizes ranging from 3.00 to 4.50 mm. The compressive strength of the SRPMSF ranged from 20.85 to 43.78 N, meeting the requirements for industrial production. The soil column leaching method was employed to assess the nutrient release rate of the fertilizers. The experimental results indicated that, compared to the PMSF, the SRPMSF effectively regulated nutrient release. Pot experiments demonstrated that the SRPMSF significantly enhanced garlic seedling growth compared to the PMSF. In conclusion, a new type of slow-release fertilizer with good slow-release performance is prepared in this paper, which can improve the utilization rate of fertilizer and reduce the economic loss and is conducive to the sustainable development of agriculture. Full article
(This article belongs to the Section Agricultural Soils)
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19 pages, 1989 KiB  
Article
Interaction Effects of Water and Nitrogen Practices on Wheat Yield, Water and Nitrogen Productivity under Drip Fertigation in Northern China
by Xin Zhang, Jianheng Zhang, Liwei Li, Yang Liu, Wenchao Zhen and Guiyan Wang
Agriculture 2024, 14(9), 1496; https://doi.org/10.3390/agriculture14091496 - 2 Sep 2024
Cited by 3 | Viewed by 1486
Abstract
Water resource shortage and unreasonable application of nitrogen (N) fertilizer have been problems in wheat production of northern China. However, the interaction effects of water regimes and N practices on wheat root growth, grain yield, soil water, and inorganic N changes as well [...] Read more.
Water resource shortage and unreasonable application of nitrogen (N) fertilizer have been problems in wheat production of northern China. However, the interaction effects of water regimes and N practices on wheat root growth, grain yield, soil water, and inorganic N changes as well as water-N use efficiency are still unclear under drip irrigation. A field experiment was conducted during the 2020–2021 and 2021–2022 winter wheat (Triticum aestivum) growing seasons. In this study, three irrigation schedules (i.e., irrigation was applied up to 80% [D1], 75% [D2], and 70% [D3] as soon as the soil water content decreased to 65%, 60% or 55% of field capacity) and two N practices (i.e., N applied at the base, jointing, booting stages were 90, 72, 48 kg ha−1 [N1], and the base, jointing, booting, filling stages were 90, 40, 40, 40 kg ha−1 [N2], respectively) were considered. The decease in irrigation water amount was offset by the increase in soil water consumption. In addition, N practices significantly interacted with irrigation on soil NO3–N accumulation (2021–2022), NH4+–N accumulation, SPAD value (2020–2021), N content in stems and grains at maturity, and average root length and weight density at the flowering stage. Irrigation, rather than N practices, significantly affected grain yield, total N uptake, crop N transformations (NT), the contribution of NT to grain (NTPC), water and N productivity, in which, for the value of these two seasons, D2 increased total N uptake by 18.1% (p < 0.05), and NT by 39.4% (p < 0.05) under N1 as compared to D3. Additionally, the highest WUE and ANUE were found in D2 during 2021–2022. Heavy irrigation water amount caused high a LAI; further analysis proved that the LAI was the key factor affecting grain yield, and positively and significantly correlated to yield. However, no significant difference in the LAI between D1 and D2 was found. N1 was beneficial to prevent N leaching and increase water and N use efficiency, biomass, and N transformation amount. This study recommends that D2 + N1 might be a promising system for manipulating irrigation and fertilization practices under sub-surface drip irrigation systems to improve water and N use efficiency and grain yields in semi-arid regions. Full article
(This article belongs to the Section Agricultural Water Management)
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17 pages, 2748 KiB  
Article
Availability of Recycled Phosphorus on Biochar Reacted with Wastewater to Support Growth of Lactuca sativa
by Kavya Laxmisagara Sagar, Daniel G. Strawn, Alex R. Crump, Martin Baker and Gregory Möller
Soil Syst. 2024, 8(3), 93; https://doi.org/10.3390/soilsystems8030093 - 28 Aug 2024
Cited by 1 | Viewed by 1233
Abstract
The use of biochar in water resource and recovery facilities (WRRF) shows promise for recovery of phosphorus (P) to use as a biochar-based fertilizer (BBF) that can replace conventional fertilizers, promote carbon sequestration, and improve soil quality. In this study, biochar was recovered [...] Read more.
The use of biochar in water resource and recovery facilities (WRRF) shows promise for recovery of phosphorus (P) to use as a biochar-based fertilizer (BBF) that can replace conventional fertilizers, promote carbon sequestration, and improve soil quality. In this study, biochar was recovered after being dosed into secondary-treated discharge from a municipal WRRF. The value of the recovered biochar as a BBF was tested in a lettuce (Lactuca sativa) growth trial. The BBF was compared to an inorganic fertilizer, raw biochar, and controls that had either only nitrogen (N) fertilizer or no amendment. The ability of the treatments to support plant growth was determined by measuring plant height, biomass, leaf tissue total N and P concentration, and plant quality. Plant quality for the Fe-modified biochar used in the WRRF was 9.05 (±0.44) on a 10-point scale compared to 9.61 (±0.46) for the inorganic fertilizer treatment and 2.22 (±0.82) for the untreated control. Plant tissue P concentrations were 6.28 (±0.83), 9.88 (±0.90), 15.46 (±2.54), and 6.36 (±1.91) g plant−1 for the raw biochar, Fe-modified biochar used in the WRRF, inorganic fertilizer, and no amendment treatments, respectively. Soil P availability and P uptake amount in the leaves indicated that the BBF released P more slowly than the inorganic P fertilizer; however, it was sufficiently available for uptake to support plant growth to maturity. Results from these experiments show that Fe-modified biochar used in WRRF can supply adequate P to plants. The slow release will reduce P leaching into surface waters. Full article
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25 pages, 3325 KiB  
Article
Effects of Paddy Rain-Flood Storage on Rice Growth Physiological Indices and Nitrogen Leaching under Organic Planting in Erhai Lake Basin
by Qingsheng Liu, Qiling Lu, Liudong Zhang, Shufang Wang, Aiqing Zou, Yong Su, Jun Sha, Ying Wang and Lihong Chen
Plants 2024, 13(17), 2381; https://doi.org/10.3390/plants13172381 - 26 Aug 2024
Cited by 2 | Viewed by 2020
Abstract
In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments [...] Read more.
In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments were set up: conventional flooding irrigation (CK) and controlled irrigation (C), with three replicates for each treatment. In 2023, aiming to enhance the utilization rate of rainwater resources and reduce the direct discharge of dry-farming tailwater from upstream into Erhai Lake. The paddy field was used as an ecological storage basin, and the water storage depth of the paddy field was increased compared to the depth of 2022. Combined with the deep storage of rainwater, the dry-farming tailwater was recharged into the paddy field to reduce the drainage. In 2023, two water treatments, flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD) were set up, and each treatment was set up with three replicates. The growth and physiological index of rice at various stages were observed. Nitrogen leaching of paddy field in surface water, soil water, and groundwater under different water treatments after tillering fertilizer were observed. The research results show that the combined application of organic and inorganic fertilizers under organic planting can provide more reasonable nutrient supply for rice, promote dry matter accumulation and other indices, and also reduce the concentration of NH4+-N in surface water. Compared with CK, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of C are increased by 4.8%, 4.1%, 20.9%, and 9.7%, respectively. Compared with CKCD, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of CCD are increased by 6.5%, 3.8%, 19.6%, and 21.9%, respectively. The yield in 2023 is 19% higher than that in 2022. Treatment C can increase the growth indicators and reduce the net photosynthetic rate to a certain extent, while CCD rain-flood storage can alleviate the inhibition of low irrigation lower limit on the net photosynthetic rate of rice. Both C and CCD can reduce nitrogen loss and irrigation amount in paddy fields. CCD can reduce the tailwater in the Gusheng area of the Erhai Lake Basin to Erhai Lake, and also can make full use of N, P, and other nutrients in the tailwater to promote the formation and development of rice. In conclusion, the paddy field rain-flood storage methodology in the Erhai Lake Basin can promote various growth and physiological indicators of rice, improve water resource utilization efficiency, reduce direct discharge of tailwater into Erhai Lake, and decrease the risk of agricultural non-point source pollution. Full article
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14 pages, 5509 KiB  
Review
Balance of Nitrate and Ammonium in Tropical Soil Conditions: Soil Factors Analyzed by Machine Learning
by Risely Ferraz-Almeida
Nitrogen 2024, 5(3), 732-745; https://doi.org/10.3390/nitrogen5030048 - 19 Aug 2024
Cited by 1 | Viewed by 2356
Abstract
The nitrogen/N dynamic is complex and affected by soil management (i.e., residue accumulation and correction/fertilization). In soil, most of the N is combined with organic matter (organic forms), but the N forms absorbed by plants are ammonium/NH4+ and nitrate/NO3 [...] Read more.
The nitrogen/N dynamic is complex and affected by soil management (i.e., residue accumulation and correction/fertilization). In soil, most of the N is combined with organic matter (organic forms), but the N forms absorbed by plants are ammonium/NH4+ and nitrate/NO3 (inorganic forms). The N recommendation for agriculture crops does not observe the N available in the soil (organic or inorganic), indicating a low efficiency in nitrogen management in soil. Based on the hypothesis that the stocks of NO3 and NH4 can be used as indicative of N status in soil but with high variation according to soil factors (soil uses and management), the objective of the study was to (i) analyze the balance of nitrate and ammonium in tropical soil with different uses and management and (ii) use machine learning to explain the nitrogen dynamic in soil and the balance of nitrate and ammonium. The results showed that soil N stocks and pH promoted the formation of three clusters with the similarity between Cluster 1 (clay texture) and Cluster 2 (loam texture), represented by higher contents of nitrate as a result of high nitrification rate and lower contents of ammonium in soil. Cluster 3 (sand texture) was isolated with different N dynamics in the soil. In agricultural soils, the content of NO3 tends to be higher than the content of NH4+. There is a high nitrification rate in clay soil explained by higher organic matter and clay content that promotes soil biology. Based on the results of machine learning, for clay and loam soil, the contents of NO3 can be used as indicative of N status as a final result of nitrification rate and higher variation in soil. However, in sandy soil, NO3 can not be used as indicative of N status due to N losses by leaching. Full article
(This article belongs to the Special Issue Soil Nitrogen Cycling—a Keystone in Ecological Sustainability)
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18 pages, 8595 KiB  
Article
Vertical Distribution of Carbon and Nitrogen in Pastures Fertilized with Broiler Litter or Mineral Fertilizer with Two Drainage Classes
by Anish Subedi, Dorcas Franklin, Miguel Cabrera, Natalia Espinoza, Nandita Gaur, Dee Pederson, Lawton Stewart and Chad Westmoreland
Soil Syst. 2024, 8(3), 85; https://doi.org/10.3390/soilsystems8030085 - 25 Jul 2024
Viewed by 1141
Abstract
Nitrogen cycling in pasture soils differing in drainage characteristics and fertilization legacy needs more research to determine efficient nutrient management strategies. This study compared differences in nitrate (NO3), ammonium (NH4+), inorganic N (IN = NO3 [...] Read more.
Nitrogen cycling in pasture soils differing in drainage characteristics and fertilization legacy needs more research to determine efficient nutrient management strategies. This study compared differences in nitrate (NO3), ammonium (NH4+), inorganic N (IN = NO3 + NH4+), potentially mineralizable nitrogen (PMN), loss-on-ignition carbon (C), and soil pH in 10, 0.7 ha pastures in Eatonton, Georgia, historically fertilized with the same amount of N as either broiler litter (BL; >15 years, 6 pastures) or mineral fertilizer (Min; 4 pastures). We sampled to 90 cm (0–5, 5–10, 10–20, 20–40, 40–60, and 60–90 cm) on a 20 m grid. An analysis of variance indicated that below 5 cm BL pastures had significantly greater amounts of NO3, IN, PMN, and soil pH compared to Min pastures. Comparisons of drainage classes (well drained~WD, moderately well drained~MWD, and somewhat-poorly drained~SPD) for each BL and Min were analyzed using linear regression for C:IN, C:PMN, pH: NO3, and pH: NH4+ with all depths combined. In MWD soils, BL had 0.1 and 0.2 mg N kg−1 greater PMN and IN, respectively, for each unit increase in C. In WD soils NO3 decreased in BL by 7.4 and in Min by 12.1 mg N kg−1, while in MWD soils, this level decreased in BL by 7.8 and in Min by 4.5 mg N kg−1 for each pH unit. Five years after N fertilization stopped, BL soils have retained more inorganic N but are losing more NO3 at a greater rate in the MWD soils when all depths are considered. These losses are a combination of plant uptake, emissions, runoff and leaching. While more research is needed, these results strongly suggest the need to design N fertilization practices with drainage class and fertilization legacy in mind to improve N-use efficiency. Full article
(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)
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22 pages, 8964 KiB  
Article
Surface Flux Patterns of Nutrient Concentrations and Total Suspended Solids in Western Carpathian Stream within Agricultural, Forest, and Grassland Landscapes
by Wiktor Halecki and Dawid Bedla
Water 2024, 16(14), 2052; https://doi.org/10.3390/w16142052 - 19 Jul 2024
Cited by 2 | Viewed by 1138
Abstract
The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid [...] Read more.
The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid (TSS) flux. Continuous rainwater inundation of soils in river valleys exacerbates this issue. Utilizing innovative tools like SWAT+, studies have revealed higher concentrations of inorganic nutrients in main watercourses from flysch catchments, with agricultural use linked to N-NO3 concentrations and pasture use linked to anion P-PO43−. Maintaining detailed records is crucial for researchers comparing data. SWAT+ proves valuable for studying TSS washing out and inorganic nutrient leaching, informing collaborative watershed management policies involving stakeholders from agriculture, conservation, and water management sectors. The insights on nutrient leaching, particularly phosphorus (P) and nitrogen (N), are instrumental for shaping policies targeting nutrient pollution within pasture land use for EU agriculture. These findings can guide policy frameworks focused on sustainable practices, especially for eco-schemes, and encourage collaborative watershed management efforts. Full article
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20 pages, 2703 KiB  
Review
The Fate and Challenges of the Main Nutrients in Returned Straw: A Basic Review
by Huandi Li, Jiang Li, Xiyun Jiao, Hongzhe Jiang, Yong Liu, Xinglang Wang and Chao Ma
Agronomy 2024, 14(4), 698; https://doi.org/10.3390/agronomy14040698 - 28 Mar 2024
Cited by 26 | Viewed by 2569
Abstract
Due to containing an abundance of essential nutrients, straw has significant potential to mitigate carbon (C), nitrogen (N), phosphorus (P), and potassium (K) deficits in soil. However, a lack of comprehensive and systematic reviews on C, N, P, and K release and conversion [...] Read more.
Due to containing an abundance of essential nutrients, straw has significant potential to mitigate carbon (C), nitrogen (N), phosphorus (P), and potassium (K) deficits in soil. However, a lack of comprehensive and systematic reviews on C, N, P, and K release and conversion from straw and on the impact of available nutrients in soils supplemented using straw-returning (SR) practices is noticeable in the literature. Therefore, we investigated straw decomposition, its nutrient release characteristics, and the subsequent fate of nutrients in soils. At early stages, straw decomposes rapidly and then gradually slows down at later stages. Nutrient release rates are generally in the K > P > C > N order. Nutrient fate encompasses fractions mineralized to inorganic nutrients, portions which supplement soil organic matter (SOM) pools, and other portions which are lost via leaching and gas volatilization. In future research, efforts should be made to quantitatively track straw nutrient release and fate and also examine the potential impact of coordinated supply-and-demand interactions between straw nutrients and plants. This review will provide a more systematic understanding of SR’s effectiveness in agriculture. Full article
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15 pages, 2888 KiB  
Article
Effects of Freeze–Thaw Cycles on Soil Nitrogen Transformation in Improved Saline Soils from an Irrigated Area in Northeast China
by Siyu Nie, Xian Jia, Yuanchun Zou and Jianmin Bian
Water 2024, 16(5), 653; https://doi.org/10.3390/w16050653 - 23 Feb 2024
Cited by 6 | Viewed by 2304
Abstract
Freeze–thaw cycles (FTCs) occur during the nongrowing season, and residual nitrogen (N) increases the risk of N loss with melting water. To study the effect of FTCs on soil N, rice fields in improved irrigated saline soil in northeast China were selected as [...] Read more.
Freeze–thaw cycles (FTCs) occur during the nongrowing season, and residual nitrogen (N) increases the risk of N loss with melting water. To study the effect of FTCs on soil N, rice fields in improved irrigated saline soil in northeast China were selected as the research subjects. Water content (10%, 20%, and 30%), different N fertilizer levels (180 and 220 kg/ha), and multiple FTCs of soil samples were used to clarify the effects of N fertilizer application and water content on N efficiency. The results indicate that, after the third FTC, the soil ammonium nitrogen (NH4+-N) level increased significantly. NH4+-N increased with an increase in the initial soil moisture content and decreased with fertilizer levels. Nitrate nitrogen (NO3-N) decreases with increasing initial soil moisture. The inorganic N increased significantly compared with that in the unfrozen stage, indicating that FTCs promote soil N mineralization. However, high fertilization rates inhibit mineralization. Analysis of variance showed that NO3-N is sensitive to the N application rate, water content, and salinity (p < 0.05). FTCs and artificial fertilization are the factors that affect N mineralization (p < 0.05). The research results are significant for preventing nitrate leaching and soil acidification during spring plowing and providing a scientific basis for fertilization systems and water environment pollution in improved saline soils. Full article
(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture III)
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14 pages, 3078 KiB  
Article
Global Meta-Analysis of Nitrate Leaching Vulnerability in Synthetic and Organic Fertilizers over the Past Four Decades
by Naila Sumreen Hina
Water 2024, 16(3), 457; https://doi.org/10.3390/w16030457 - 31 Jan 2024
Cited by 11 | Viewed by 6175
Abstract
The significance of nitrogen in agricultural ecosystems cannot be overstated; however, it can pose a threat to the environment when it leaches into groundwater. This comprehensive meta-analysis sheds light on the complex relationship between organic and inorganic fertilizers and nitrogen leaching, encompassing 39 [...] Read more.
The significance of nitrogen in agricultural ecosystems cannot be overstated; however, it can pose a threat to the environment when it leaches into groundwater. This comprehensive meta-analysis sheds light on the complex relationship between organic and inorganic fertilizers and nitrogen leaching, encompassing 39 years of data. The results indicate that the impact of fertilizers is dependent on crop type, soil properties, and fertilization practices. Vegetables treated with synthetic fertilizers were found to have the highest levels of nitrogen leaching, while grasses exhibited the lowest. Soil texture was also determined to be a significant factor, with coarser soils leading to higher levels of leaching than medium or fine soils. The meta-analysis showed that organic sources resulted in an average of 16% higher losses of nitrate-N, but there was no significant difference between organic and synthetic N fertilizers in terms of leaching overall. These findings provide valuable insights for the responsible management of nitrogen and to further our understanding of the impact of fertilizers on nitrate pollution. Full article
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19 pages, 4433 KiB  
Article
The Effect of Plant Growth-Promoting Rhizobacteria on Soil Properties and the Physiological and Anatomical Characteristics of Wheat under Water-Deficit Stress Conditions
by Abdulaziz A. Alaskar and Hind A. AL-Shwaiman
Agriculture 2023, 13(11), 2042; https://doi.org/10.3390/agriculture13112042 - 24 Oct 2023
Cited by 7 | Viewed by 2849
Abstract
This study aimed to evaluate the effects of plant growth-promoting Rhizobacteria (PGPR) treatments, B1, Azosprillium lipoferum Sp2 and B2, A. lipoferum Sp2 + Pseudomonas sp. SARS12, as well as inorganic nitrogen doses (60, 100, 140 and 180 kg N ha–1) on [...] Read more.
This study aimed to evaluate the effects of plant growth-promoting Rhizobacteria (PGPR) treatments, B1, Azosprillium lipoferum Sp2 and B2, A. lipoferum Sp2 + Pseudomonas sp. SARS12, as well as inorganic nitrogen doses (60, 100, 140 and 180 kg N ha–1) on some soil physical characters, physiological, anatomical and yield parameters as well as nitrogen use efficiency (NUE) of wheat under water deficit stress. Results showed that water stress significantly decreased physiological characters such as chlorophyll content (6.7 and 9.8%) and relative water content (13.7 and 11.2%) in both seasons, respectively. Nevertheless, proline and malondialdehyde (MDA) were increased significantly (26.9, 12.3% and 90.2, 96.4%) in both seasons, respectively, as signals for water stress. The anatomical characteristics of flag leaves were negatively affected. Inoculation of wheat grains with PGPR significantly increased field capacity and RWC, adjusted enzymes’ activity and thus improved the physiological and yield traits and NUE as well as improving the anatomical features of flag leaves. Moreover, the combination of integrated PGPR and 140 kg N ha−1 significantly improved grain yield and its components as well as grain N uptake in comparison to control treatments. In conclusion, PGPR improved wheat productivity and NUE; they are an eco-friendly and cost-effective approach for improving plant production, and reducing nutrient leaching hazards and the negative impact of water stress. Full article
(This article belongs to the Special Issue The Role of Plant Growth-Promoting Bacteria in Crop Improvement)
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13 pages, 349 KiB  
Article
Annual Ryegrass (Lolium multiflorum Lam.) Growth Response to Nitrogen in a Sandy Soil Amended with Acidified Manure and Municipal Sludge after “Quick Wash” Treatment
by Wooiklee S. Paye, Ariel A. Szogi, Paul D. Shumaker and Eric D. Billman
Agronomy 2023, 13(10), 2655; https://doi.org/10.3390/agronomy13102655 - 22 Oct 2023
Cited by 3 | Viewed by 2102
Abstract
The Quick Wash (QW) treatment extracts phosphorus (P) from manure and municipal sludge (MS), producing an organic acidified by-product with adequate nitrogen (N):P ratio to meet crop N requirements. Yet, data on crop response to N using QW by-products are lacking. We evaluated [...] Read more.
The Quick Wash (QW) treatment extracts phosphorus (P) from manure and municipal sludge (MS), producing an organic acidified by-product with adequate nitrogen (N):P ratio to meet crop N requirements. Yet, data on crop response to N using QW by-products are lacking. We evaluated the response of annual ryegrass (Lolium multiflorum Lam.) and potential N leaching in sandy soil to N applications using raw wastes, their corresponding QW by-products, and ammonium sulfate (AMS) fertilizer. Treatments included a control (no amendment added), raw and acid-washed chicken litter, dairy and swine manure, MS, and AMS at 100, 200, and 400 kg N ha−1. We found no significant differences in annual ryegrass yield and N uptake between the raw and acidified organic QW by-products. However, ryegrass produced 4–30% more biomass with AMS than organic amendments. The total residual soil inorganic N under AMS treatments ranged between 6.3 and 67.9 mg pot−1 and accounted for 5–17% of the total N applied, but it was <1% for all the organic amendments. We found no differences in soil N leaching between raw and acid-washed forms of each organic soil amendment. Our results indicated that acidified organic QW by-products can improve environmental quality by substantially reducing the amount of applied P with no penalties for crop yield losses compared to raw manure and MS. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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